Unit 8 · Detecting Reasoning Errors
Tang Family Planning — Reverse Inference
Lesson 19 of 34
About this lesson
Three weather rules. One forecast. Victor thinks the indoor market proves it rained. Aidan thinks the beach proves the forecast was right. The difference? The beach has only ONE possible cause — the indoor market has two.
Chapters
Question
The Tang family are planning a day out tomorrow. They will decide where to go based on the weather in the morning. There are three possibilities:
- If it’s sunny in the morning, they’ll visit their aunt who lives by the beach.
- If it’s raining, they’ll go to the indoor market to do some shopping.
- If it’s overcast but not raining, they will head into town. They might still go to the indoor market but they definitely won’t go to the beach.
The weather forecast for tomorrow morning is for sunshine.
Victor said: “If you see the Tangs in the indoor market tomorrow, it must mean it’s been raining.”
Aidan said: “If you see them at the beach, it must mean the weather forecast was correct.”
If the information in the box is true, whose reasoning is correct?
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